the benefits of combining paper-and video-based prototypes for … · 2020-05-15 · explored. the...

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The Benefits of Combining Paper-and Video-BasedPrototypes for User Interface Evaluation

Hayet Hammami, Fatoumata Camara, Gaëlle Calvary, Meriem Riahi, FaouziMoussa

To cite this version:Hayet Hammami, Fatoumata Camara, Gaëlle Calvary, Meriem Riahi, Faouzi Moussa. The Benefitsof Combining Paper-and Video-Based Prototypes for User Interface Evaluation. 2020. �hal-02554507�

https://hal.archives-ouvertes.fr/hal-02554507

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The Benefits of Combining Paper- and Video- Based Prototypes for User Interface

Evaluation

Hayet Hammami†∗, Fatoumata Camara§, Gaelle Calvary∗, Meriem Riahi† and Faouzi Moussa†∗Univ. Grenoble Alpes, CNRS, Grenoble INP, LIG

F38000 Grenoble FranceEmail: [email protected]

†Univ. of Tunis El Manar, Faculty of sciences of Tunis, LIPAH-LR11ES142092 Tunis Tunisia

Email: [email protected], [email protected]§HWR Berlin, Berlin Germany

Email: [email protected]

Abstract—The use of multiple User Interface (UI) designs forevaluation has been demonstrated beneficial for UI evaluation asit results in better feedback, both qualitatively and quantitatively.However, producing several designs is time-consuming. Moreover,the properties that the alternative UI must satisfy remain under-explored. The paper investigates the use of different prototypeforms of the same design as support to evaluation insteadof relying on alternative design solutions. We investigate twoexperimental conditions: (1) paper prototype first then videoprototype, and (2) video prototype first then paper prototype.Results show that the combination of paper and video prototypesis well suited for UI evaluation, as feedback addresses allaspects of Human-Computer Interaction (HCI), namely, utility,usability, and aesthetics. When exposed to multiple prototypes,users develop an understanding of the functional core and ofthe interactive aspect of the system. The experiment outcomesindicate that, when evaluating the paper prototype first, then thevideo prototype, users tend to be more critical and provide moresuggestions of improvements.

Keywords–UI evaluation; Feedback; Prototyping; Video proto-typing; Comparative evaluation.

I. INTRODUCTION

The number of UI designs used for evaluation influencesresponsiveness of users as well as the amount and qualityof feedback. Therefore, submitting different design examplescould help UI testers see issues clearly, identify concrete stepsfor improvement, and integrate novel ideas [1].

Many research papers addressed the use of multiple designalternatives for UI evaluation (comparative evaluation) [1]–[5].These alternatives consist of design variations at several levelsof abstraction, such as syntactic and semantic levels. They canbe designed by the same designer(s) [2] [4], or obtained viatargeted research such as the visual aspects or the content [1].

Comparative evaluation increases the amount of comments(reviews and suggestions), gives rise to more and stronger crit-icisms, and facilitates comparative reasoning. Consequently,showing multiple design alternatives to users for UI evaluationrepresents a way to get the right design.

Previous work clearly highlights that comparative eval-uation has great benefits. However, producing alternativedesign(s) can be time-consuming and difficult, particularlyconsidering that existing literature does not address criteria

that should be considered for the generation of the alternativedesign(s).

In this work, we investigate the use of different prototypeforms as support to evaluation. Our aim is to determinewhether the use of different forms could be as beneficial asdifferent designs so that it could be considered as an alternativeto multiple designs for evaluation. In this paper, we report anexperimental evaluation in which we used both paper and videoas prototype mediums for UI evaluation.

The remaining of this paper is organized as follows. SectionII presents related work about system prototyping. Section IIIdescribes the experiment and the design elaboration. SectionIV reports results and observations from the experiment andSection V concludes the paper and presents future work.

II. MANY FACES OF PROTOTYPING

Prototypes can be of different levels of fidelity and cantake different forms. The right level of fidelity and appropriateform of a prototype depends on the design stage and evaluationneeds. A prototype can be of low-fidelity, medium-fidelity orhigh-fidelity with respect to the final UI [6]. According toGreenberg [7], “The determining factor in prototype fidelityis the degree to which the prototype accurately represents theappearance and interaction of the product”.

Much of the often-cited literature emphasizes the use oflow/medium fidelity prototypes [8] [9]. When assessing lowfidelity prototypes, users feel more included in the design pro-cess and feel more free to criticize the design [10]. Oppositely,when evaluating high fidelity prototypes for the first time, userstend to focus on the details of the interface (e.g. color oficons, size of font) rather than on the overall structure [7].Furthermore, it has been found that the usability data collectedfrom low and high-fidelity levels are comparable [9] [10] [11].

Moreover, a prototype can take different forms, such as asketch [8], a paper mock-up [4] or a tool to test [12]. Designerscan also use presentation software like PowerPoint or Keynote[13], or videos [14] [15] in order to illustrate the dynamicityof interaction.

A. Paper prototypingTechniques such as paper prototyping excel at representing

static visual properties [15]. They are very used during the

193Copyright (c) IARIA, 2020. ISBN: 978-1-61208-761-0

ACHI 2020 : The Thirteenth International Conference on Advances in Computer-Human Interactions

design process due to their low cost and efficiency. They canperform the role of sketching in order to develop, explore,communicate and evaluate the designer’s ideas [2] [8].

Paper prototyping presents a fast and easy way to commu-nicate and to test initial ideas early and quickly, e.g., brain-storming sessions. Paper prototypes help in getting substan-tive user feedback, promote rapid iterative development [10],and allow for easy and inexpensive modifications. Moreover,paper prototypes can be very helpful for usability testing asmentioned in Tohidi et al.’s work: “the interaction designercommunicates with the user largely by means of an “interac-tive sketch”, such as a paper prototype” [8].

B. Video prototypingVideo prototypes, on the other hand, are particularly well

suited to assess interaction. Video prototyping is an establishedtechnique in HCI, which is typically used in early designsstages to enable software designers to evaluate the interactionprior to actual software implementation. Producing a videoprototype is cheaper and less time-consuming in comparisonto building a fully working prototype.

Video prototypes present great benefits [11] [14]–[17],for instance, they allow design exploration, evaluation andpresentation [16] [17]. They also communicate and reflect theinteraction design [15] and help capture and communicate thedetails of how users interact with software. Zwinderman etal. [18] compared the use of video prototypes and usabilitytests. They analyzed results regarding overall user experience(AttrackDiff), user acceptance (Unified Theory of Acceptanceand Use of Technology (UTAUT)), and five “expectations”elaborated by the researchers in this work:

• Participants who use the product give more commentson the interface.

• Viewers of the video prototype make more commentson the context of use.

• Participants provide a similar number of comments asto when and where they use the application.

• Viewers of the video prototype suggest more newfeatures.

• Participants who use the product suggest more im-provements.

The conclusion of this study suggests that video prototypeshelp obtain feedback from users that is quite similar to thatgathered when users test the final product.

In other works, researchers studied the impact of the visualfidelity-level of video prototypes on the amount and quality offeedback provided by users during evaluation. Dhilton et al.[11] compared feedback collected from using a low-fidelityvideo prototype (animated paper cut-outs) and feedback col-lected from using a high-fidelity video prototype (a video withreal actors, edited to simulate computer output). The videoprototype fidelity focused on the notion of realism of the video(Figure 1). Analysis considered attractiveness and usabilityof the concept (AttrackDiff), intent to use, understandability,ease of use and feasibility of the system presented (UTAUT).Additionally, during test sessions, users were asked to expresslikes and dislikes related to the system as well as suggestionsfor improvement. Dhilton et al.’s study concludes that thevisual fidelity level of the video prototype does not affect

Figure 1. Low fidelity (left) and high fidelity (right) versions of the videoprototype used in [11].

the amount and quality of user’s feedback during evaluationsessions.

Both paper and video prototypes foster discussion regard-ing interface and interaction with stakeholders. Video proto-types represent a powerful tool as they produce feedback thatcan be compared to feedback from other techniques that mightbe more costly. Both paper and video prototypes are cheap toproduce and have been proven beneficial for HCI evaluation.However, to the best of our knowledge, the combined use ofpaper and video prototypes as support to HCI evaluation hasnot yet been investigated (particularly as alternative to usingmultiple design alternatives).

In this work, we use a paper prototype and a videoprototype to assess a commercial Website. We investigate thebenefits of using both prototype forms presented together in thesame evaluation session for UI evaluation. The main researchquestion tackled here is the following: “does using differentprototype types as support to HCI evaluation could be asbeneficial as relying on alternative UI designs?”.

III. EXPERIMENT

Our study focused on a commercial Web site for high-techproducts. The case study was purely academic. The reason forthis choice was that the e-commerce platform is widespreadand familiar to many people, and thereby easy to explain.

A. Prototypes elaborationThe prototypes consisted of medium fidelity prototypes,

designed using the Balsamiq Wireframes tool [19]. The UIillustrates essential features of the commercial Web site: menu,sub-menus, list of items on the home page, list of items for aspecific category of products, details of a product, and contentof the cart.

The paper prototype (Figure 2) consisted of four screen-shots, illustrating four different pages of the Web site. Figure2-A represents the home page of the Web site, Figure 2-Brepresents the page referring to the sub-category smartphones,Figure 2-C represents the page referring to the details of aselected product, and Figure 2-D represents the page referringto the cart. Using a tool like Balsamiq allowed us to assignhypertext links to different components of the interface in orderto create functional widgets and navigate between the differentpages.

The video prototype was then made by recording interac-tion through the same UI, using a video screenshot tool. Therewere no additional pages shown on the video. However, insome cases, the products displayed changed due to navigationin the list (Figure 3).



A. Home page B. Smartphone category page

C. Article details page D. Cart page

Figure 2. Paper-based prototype presented to users

Figure 3. Video based prototype

B. ScenarioThe video is 42 seconds long and features a user choosing

and purchasing a smartphone through the Web site. Thescenario goes as follows: the user starts by navigating throughthe home page of the Web site, browsing the deals and thebest sellers’ lists, then, he/she browses the menu to explore thedifferent categories and sub-categories presented, and selectsthe sub-category “smartphone”. Next, we see the user beingredirected to the smartphone sub-category page, from wherehe/she can choose a product from the list and add it to the cart.After consulting the cart, we see the user changing his/hermind about the product that he/she selected. He/she deletesit from the cart and goes back to the home page to choose

another item.

The same person who designed the UI was the one whoran the scenario for the video.

C. Participants

The technique used for our experiment is primarily a qual-itative one, but which allows to collect quantitative data. Withqualitative techniques, such as usability tests or interviews,the aim is to dig into topics (i.e., usability problems) whileusually observing testers’ reactions: as the name implies, thefocus is more on quality rather than on quantity. Consequently,qualitative techniques require a low number of testers to geta fair overview over the addressed topics; for instance, as lowas 5 participants for a usability tests [20]. Indeed, according toNielson [20], “with 5 users, we almost always get close to usertesting’s maximum benefit cost ratio”. However, it is importantto mention that, to get statistically significant numbers, atleast 20 participants should be included in the study. Folkler[21] suggest that 20 participants help obtain 95% of usabilityproblems.

Our experiment involved 22 participants (11 women and11 men, with a range of age between 22 and 58 years old).Participants included both HCI students and researchers as wellas people with no knowledge at all in the field. The numberof HCI students, females and males were equivalent for eachgroup of participants.

Participants were asked about their online shopping fre-quency. 13 participants said that they often purchase productsonline, 7 participants said that they sometimes do online



shopping, and 2 participants said that they rarely purchaseproducts online.

D. ProtocolWe considered two experimental conditions: paper proto-

type, then video prototype and video prototype, then paperprototype. Participants were divided into two groups of elevenparticipants, and were asked to observe and critique bothprototypes. Each group tested one experimental condition:

• Experimental condition 1: paper prototype, thenvideo prototype: participants were first provided withthe paper-based prototype and asked to observe theUI without enforcing any time limit. After looking atthe prototype, the participants were asked to evaluateit. As a second step, we replaced the paper-basedprototype with the video and asked the participantto watch it. The video could be watched up to threetimes at most. It was up to the participant to re-watch.However, it was not allowed to pause the video whilewatching. After watching the video, the participantswere asked if they had something to add regardingtheir first evaluation.

• Experimental condition 2: video prototype, thenpaper prototype: participants were first presentedwith the video then with the paper-based prototype.

E. Users feedback recordParticipants were asked to provide feedback using their

own words regarding three aspects: things they like, thingsthey do not likee and improvements. To do so, they had towrite their statements on magnetic post-its and place them aseither ‘like’, ‘dislike’ or ‘improvement’ on a board (Figure 4).

Figure 4. Participant expressing his opinions

Most of the time, participants tended to explain what theyare writing and expressed their thoughts orally. Observationswere recorded by note-taking throughout the experiment. Fur-thermore, we recorded the evaluation sessions via a Dicta-phone.

IV. RESULTS

This section presents the results of the experiment. We firstclassify users’ feedback, then we discuss the impacts of the twotypes of prototyping on the UI evaluation.

A. Categorization of user’s feedbackWe collected, counted, and classified users’ statements in

three categories with respect to the ones that were consideredto collect feedback: likes (positive comments), dislikes (neg-ative comments) and suggestions for improvement. This firstcategorization was inspired by the taxonomy elaborated in [2],and used in [4]. We used it to study the user’s willingnessto criticize during evaluation sessions. Then, we gatheredstatements inductively according to three criteria commonlyconsidered in UI evaluation: utility, usability and aesthetics, inorder to study users’ feedback.

The total number of statements collected for both groupswas approximately the same: 106 for the first group (paperthen video) and 104 for the second group (video then paper).

As indicated in Table 1, in both experimental conditions,the number of statements provided with the prototype beingpresented at first was significantly higher than the number ofstatements collected with the second prototype. Indeed, duringthe first step of the evaluation, regardless whether the paperor the video prototype was presented first, the number ofstatements was roughly the same.

TABLE I. NUMBER OF STATEMENTS.

Step 1 Step 2 Total number of statementsGroup 1 (Paper then video) 77 29 106Group 2 (Video then paper) 79 25 104

B. Impact on user’s willingness to criticize depending on theprototype presented and evaluation condition

In order to assess the impacts of presenting different formsof prototypes on participants’ willingness to be critical, wecompared the number of positive comments, negative com-ments and suggestions for improvement according to the orderof prototypes presentation: paper then video (group 1) andvideo then paper (group 2).

Figure 5 shows how the total numbers of statementsproduced were classified. The first observation in Figure 5 is

Figure 5. Numbers of positive comments (likes), negative comments(dislikes), and suggestions

that the number of likes and suggestions are higher than thenegative comments for both groups. However, it is importantto note that the number of dislikes added to the number



of suggestions is higher than the number of likes for eachprototype for both groups.

The number of dislikes is significantly lower than the num-bers of likes and suggestions. This result can be explained bythe overlap between dislikes and suggestions. Indeed, duringthe experiment, participants often hesitated to choose betweendislikes and suggestions for many comments.

Examples of likes included feedback about the access tobest sellers on the welcome page and the simplicity of the UI.Examples of suggestions included feedback about integratinga more sophisticated search function and using vertical insteadof horizontal scrolling. Examples of dislikes included feedbackabout the lack of the navigation menu in the cart page and thelack of the “add” button in the best deals list.

An important observation is that the feedback collected inthe second step of the evaluation for both groups consistedmainly in suggestions and negative comments. Indeed, reeval-uating the same UI design, but, presented through a differenttype of prototype pushed users to be more critical and toprovide more insights about improvements.

Overall, Overall, regardless of what prototype was pre-sented first, users started by expressing their likes and ap-preciations of the prototype in question. However, users inthe first group provided more suggestions in the second stepof the evaluation than the second group. Seeing the videoprototype after the evaluation of the paper prototype pushedusers to be more critical and to provide more suggestions forimprovements.

Based on these results, we can say that the experimenthighlighted the positive aspects of the design, while alsogathering an even greater number of insights for design im-provement.

C. Impact on users’ feedback depending on the prototypepresented and evaluation condition

We qualitatively analyzed the data in order to relate par-ticipants’ statements to utility, usability and aesthetics withineach prototype and evaluation order. Feedback about utilityaddressed the system features, including comments such asdeleting or adding a feature to the Web site. We consid-ered usability as defined by the International Organizationfor Standardization (ISO): “The extent to which a productcan be used by specified users to achieve specified goalswith effectiveness, efficiency, and satisfaction in a specifiedcontext of use” [22]. Feedback regarding usability included,for instance, the possibility to add a product directly from thewelcome page; the absence of the navigation menu in the cartpage; the possibility to add several products to the cart at thesame time; or, the absence of an information message oncea product is added or deleted from the cart. Feedback aboutaesthetics considered the graphic design (e.g., colors, iconsdesign, fonts, widget choices, etc.) and included statementsabout the choice of the icon chosen as the Web site logo andthe colors used.

Figure 6 shows how the total number of statements pro-duced were classified.

Results show that the paper prototype produced the highestnumber of feedback related to utility whilst the video prototypeproduced the highest number of feedback related to usability.

Figure 6. Numbers of statements according to utility, usability, andaesthetics.

Figure 7. Numbers of statements according to utility, usability, andaesthetics for the first evaluation order (paper then video).

Finally, the numbers of feedback regarding aesthetics areroughly the same for the two prototypes over the two groups.

Furthermore, we summarize below the qualitative dataproviding indications according to the two mentioned classifi-cations in order to compare the number of problems discov-ered and suggestions provided regarding each aspect (utility,usability and aesthetics) for each prototype for both groups.

Figures 7 and 8 show how the total numbers of statementsproduced were classified.

Results show that participants detected more problems andprovided more suggestions in experiment condition 1 (paper

Figure 8. Numbers of statements according to utility, usability, andaesthetics for the second evaluation order (video then paper).



then video) than in experiment condition 2 (video the paper).For example, the number of likes regarding usability providedwith the video prototype in the second group was similar tothe number of dislikes and suggestions provided about thisHCI aspect. However, in the first group, when comparing thenumber of likes with the number of dislikes and suggestionsabout utility, we find that the number of likes is considerablylower.

V. CONCLUSION AND FUTURE WORKThis study explores a different approach to UI evaluation,

which could guide practitioners towards getting the designright while minimizing the cost of UI design.

We conducted an experiment which consisted in using amedium-fidelity paper prototype and a medium-fidelity videoprototype as support to evaluation and tested two experimentalconditions. Users successively evaluated either a paper proto-type then a video prototype, or a video prototype then a paperprototype.

The results indicate that (1) using paper prototypes allowedusers to focus on features offered by the system ; actually,users took time to explore the system features, as such,they developed an understanding of the functional core andcriticized mainly utility. (2) Using a video prototype allowedusers to focus more on the interaction with the system, i.e.,how a user can perform a specific task; as such, by seeingthe system ‘in action’, they developed an understanding ofthe interactive aspects of the system and focused on usability.(3) Regarding aesthetics, feedback provided by users wascomparable within both groups.

Moreover, it is important to note that the order of proto-types presentation to users does matter since evaluating thevideo prototype after evaluating the paper prototype incitesusers to be more critical and to provide more suggestions ofimprovements.

Overall, the results indicate that evaluating one prototype isnot enough. Over both evaluation conditions, when seeing theUI in a different prototype form, users discovered problemsand provided suggestions of improvements that did not occurto them when evaluating the first prototype provided.

A general recommendation coming out of this study is tosupplement video prototypes with paper prototypes at first forUI evaluation, in order to increase the evaluation benefits.

In future work, we are interested in comparing evaluationbased on different types of prototypes and evaluation basedon alternative design solutions in order to identify the mostbeneficial approach in terms of relevant feedback at a minimumcost.

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